Aside from the places where I have corrected it, I think that your grammar, for the most part, is fine. However, I did reword some sections and add some words (my additions are in brackets below) to make it either more grammatical or else simply to flow better. There are a few parts that are not altogether clear (eg, what is a “well-thinking skill”?) and you may want to revise these as well. You can send me another draft if you like
English is [quite] hard [f]or me especially in writing.
[Recently], English has become a global language [and is increasingly used for communication in a broad variety of fields]. As we can see [,]almost every field in Thailand [,including] education, business, medicine, and even entertainment are all related to English. Consequently, [learning how to use the] English language effectively is very important to Thai people. Therefore, almost all [of the] schools in Thailand [must] include English [as a] subject in the curriculum from grade 1 [onwards]. [This] means [that] Thai students are required to study English [for] at least nine years. [However], despite the fact that they have studied English for several years, [most] Thai people cannot communicate fluently in English.
The first reason for this is the limited time devoted to English in Thai schools (about 3-5 hours [of] English class per week). Consequently, children do not have much time to learn and practice English. As we all know, it is [impossible] to add more English class hours into the Thai schools’ curriculum because they are already overloaded. The solution to this problem might [be] to adjust the curriculum [so that students are forced] to study in English program[s] at [an] early age[,] like in international schools. This method might help students [start] learning and using English more effectively.
Another significant reason students cannot communicate in English is [that] they do not have a well-thinking skill which leads them to face a hard situation in speaking [when they are] afraid of making mistakes and los[ing] face in public. I believe in the saying that “We cannot think unless we have memories”. In order to improve students’ thinking skill[s] [and increase their efficiency in English], they [will need] to memorize many grammatical rules, [a large vocabulary] and numerous idiomatic expressions. When they are able to manage these, they will be able to think [systematically] and be able to speak fluently.
In conclusion, for [the] two reasons mentioned above, students are not able to improve their English skills [effectively]. Students must have a strong will in learning and practicing a lot of English. Besides learning in a classroom, [this] can be done in several ways. [For example, effective practice techniques can include] listening to English news channels such as BBC and CNN, learning from online English lesson[s] on the internet, reading English newspapers and so on. Once they are good at English, they must keep learning and practicing it, otherwise they will forget what they have learned.
Student or Learner